A direct current (DC) to direct current converter is an electronic circuit that converts an input DC supply voltage into a DC output voltage that is higher or lower in magnitude than the input DC supply voltage. A DC to DC converter that generates an output voltage lower than the input voltage is termed a buck or step-down converter. A DC to DC converter that generates an output voltage higher than the input voltage is termed a boost or step-up converter. A typical DC to DC converter includes a switch for alternately opening and closing a current path through an inductor in response to a switching signal. In operation, a DC voltage is applied across the inductor. Electrical energy is transferred to a load connected to the inductor by alternately opening and closing the switch as a function of the switching signal. The amount of electrical energy transferred to the load is a function of the duty cycle of the switch and the frequency of the switching signal. DC to DC converters are widely used to power electronic devices, particularly battery-powered devices, such as portable cellular phones, laptop computers, and other electronic systems in which efficient use of power is desirable.
Energy harvesting is the process by which energy is derived from external sources, such as solar power, wind energy, kinetic energy, and thermal energy, captured, and stored. Energy harvesting may be utilized in small, wireless devices such as devices in wireless sensor networks. Typically, an energy harvesting system collects ambient energy and utilizes a boost DC to DC converter to provide a higher output voltage than provided by the ambient source. The voltage then may be stored in a storage element.
A typical power management system utilizes a low-dropout regulator (LDO) to lower output voltage from the storage element which is to be provided to a load. The LDO operates as a resistive voltage divider. Thus, a large amount of power may be lost in regulation. This may be problematic, especially for low power applications.